| 摘要 |
PROBLEM TO BE SOLVED: To obtain a zoom lens hardly causing image degradation even when vibration-proofing, and maintaining an excellent image when compensated. SOLUTION: The zoom lens has first, second, third and fourth lens groups having positive, negative, positive and positive refractive power in order from an object side to an image side. The third lens group comprises a third-a lens group having negative refractive power, and a third-b lens group having positive refractive power. In zooming, the second and the fourth lens groups move on an optical axis, and the third-b lens group is moved in a direction having a component of a perpendicular direction to the optical axis so as to displace an image in the perpendicular direction to the optical axis. The third-a lens group comprises a negative lens G3an whose both surfaces are spherical and a positive lens whose both surfaces are spherical, and the third-b lens group has a positive lens G3bp including an aspherical lens surface and a negative lens. The refractive index of the material of the negative lens G3an and the positive lens G3bp is appropriately set. COPYRIGHT: (C)2008,JPO&INPIT
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